Temperature has obvious effects on the tested results of frequency domain dielectric spectrum (FDS) method. To estimate the moisture content of field oil-immersed bushing, the effects of temperature must be considered and eliminated. In this study, the frequency-domain dielectric spectrum of 72.5 kV bushing samples with different moisture contents was tested at different temperatures. The law that temperature affects the results of FDS tests was analysed and concluded. Afterwards, a method to transfer the tested results to the reference temperature (15°C) was proposed. Finally, an estimation method of moisture content for field oil-immersed bushing was proposed and testified. The following conclusions can be concluded: (i) the effects of temperature on the FDS results may be divided into two aspects, i.e. one is along the horizontal axis and the other is along the vertical axis and (ii) based on the proposed method, the temperature effects on the results of FDS tests can be eliminated, and the moisture content of field oil-immersed bushing can be estimated effectively and feasibly.